From f53f3eee9f8e41a4fd927eb6f4dbf41b8e0475dd Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Sun, 22 Apr 2018 18:09:02 +0900
Subject: [PATCH] implement parsing and writing of the PATH_CHALLENGE frame

---
 internal/wire/frame_parser.go              |  5 +++
 internal/wire/frame_parser_test.go         | 12 ++++++
 internal/wire/path_challenge_frame.go      | 39 ++++++++++++++++++
 internal/wire/path_challenge_frame_test.go | 47 ++++++++++++++++++++++
 4 files changed, 103 insertions(+)
 create mode 100644 internal/wire/path_challenge_frame.go
 create mode 100644 internal/wire/path_challenge_frame_test.go

diff --git a/internal/wire/frame_parser.go b/internal/wire/frame_parser.go
index 041a64d5..b4409532 100644
--- a/internal/wire/frame_parser.go
+++ b/internal/wire/frame_parser.go
@@ -90,6 +90,11 @@ func parseIETFFrame(r *bytes.Reader, typeByte byte, v protocol.VersionNumber) (F
 		if err != nil {
 			err = qerr.Error(qerr.InvalidAckData, err.Error())
 		}
+	case 0xe:
+		frame, err = parsePathChallengeFrame(r, v)
+		if err != nil {
+			err = qerr.Error(qerr.InvalidFrameData, err.Error())
+		}
 	default:
 		err = qerr.Error(qerr.InvalidFrameData, fmt.Sprintf("unknown type byte 0x%x", typeByte))
 	}
diff --git a/internal/wire/frame_parser_test.go b/internal/wire/frame_parser_test.go
index e6d9a4c0..c081b715 100644
--- a/internal/wire/frame_parser_test.go
+++ b/internal/wire/frame_parser_test.go
@@ -289,6 +289,17 @@ var _ = Describe("Frame parsing", func() {
 			Expect(frame.(*AckFrame).LargestAcked()).To(Equal(protocol.PacketNumber(0x13)))
 		})
 
+		It("unpacks PATH_CHALLENGE frames", func() {
+			f := &PathChallengeFrame{Data: [8]byte{1, 2, 3, 4, 5, 6, 7, 8}}
+			err := f.Write(buf, versionIETFFrames)
+			Expect(err).ToNot(HaveOccurred())
+			frame, err := ParseNextFrame(bytes.NewReader(buf.Bytes()), nil, versionIETFFrames)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(frame).ToNot(BeNil())
+			Expect(frame).To(BeAssignableToTypeOf(f))
+			Expect(frame.(*PathChallengeFrame).Data).To(Equal([8]byte{1, 2, 3, 4, 5, 6, 7, 8}))
+		})
+
 		It("errors on invalid type", func() {
 			_, err := ParseNextFrame(bytes.NewReader([]byte{0xf}), nil, versionIETFFrames)
 			Expect(err).To(MatchError("InvalidFrameData: unknown type byte 0xf"))
@@ -306,6 +317,7 @@ var _ = Describe("Frame parsing", func() {
 				0x0a: qerr.InvalidFrameData,
 				0x0c: qerr.InvalidFrameData,
 				0x0d: qerr.InvalidAckData,
+				0x0e: qerr.InvalidFrameData,
 				0x10: qerr.InvalidStreamData,
 			} {
 				_, err := ParseNextFrame(bytes.NewReader([]byte{b}), nil, versionIETFFrames)
diff --git a/internal/wire/path_challenge_frame.go b/internal/wire/path_challenge_frame.go
new file mode 100644
index 00000000..f2a27d84
--- /dev/null
+++ b/internal/wire/path_challenge_frame.go
@@ -0,0 +1,39 @@
+package wire
+
+import (
+	"bytes"
+	"io"
+
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+)
+
+// A PathChallengeFrame is a PATH_CHALLENGE frame
+type PathChallengeFrame struct {
+	Data [8]byte
+}
+
+func parsePathChallengeFrame(r *bytes.Reader, version protocol.VersionNumber) (*PathChallengeFrame, error) {
+	if _, err := r.ReadByte(); err != nil {
+		return nil, err
+	}
+	frame := &PathChallengeFrame{}
+	if _, err := io.ReadFull(r, frame.Data[:]); err != nil {
+		if err == io.ErrUnexpectedEOF {
+			return nil, io.EOF
+		}
+		return nil, err
+	}
+	return frame, nil
+}
+
+func (f *PathChallengeFrame) Write(b *bytes.Buffer, _ protocol.VersionNumber) error {
+	typeByte := uint8(0x0e)
+	b.WriteByte(typeByte)
+	b.Write(f.Data[:])
+	return nil
+}
+
+// Length of a written frame
+func (f *PathChallengeFrame) Length(_ protocol.VersionNumber) protocol.ByteCount {
+	return 1 + 8
+}
diff --git a/internal/wire/path_challenge_frame_test.go b/internal/wire/path_challenge_frame_test.go
new file mode 100644
index 00000000..bbfc7109
--- /dev/null
+++ b/internal/wire/path_challenge_frame_test.go
@@ -0,0 +1,47 @@
+package wire
+
+import (
+	"bytes"
+	"io"
+
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("PATH_CHALLENGE frame", func() {
+	Context("when parsing", func() {
+		It("accepts sample frame", func() {
+			b := bytes.NewReader([]byte{0x0e, 1, 2, 3, 4, 5, 6, 7, 8})
+			f, err := parsePathChallengeFrame(b, protocol.VersionWhatever)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(b.Len()).To(BeZero())
+			Expect(f.Data).To(Equal([8]byte{1, 2, 3, 4, 5, 6, 7, 8}))
+		})
+
+		It("errors on EOFs", func() {
+			data := []byte{0x0e, 1, 2, 3, 4, 5, 6, 7, 8}
+			_, err := parsePathChallengeFrame(bytes.NewReader(data), versionIETFFrames)
+			Expect(err).NotTo(HaveOccurred())
+			for i := range data {
+				_, err := parsePathChallengeFrame(bytes.NewReader(data[0:i]), versionIETFFrames)
+				Expect(err).To(MatchError(io.EOF))
+			}
+		})
+	})
+
+	Context("when writing", func() {
+		It("writes a sample frame", func() {
+			b := &bytes.Buffer{}
+			frame := PathChallengeFrame{Data: [8]byte{0xde, 0xad, 0xbe, 0xef, 0xca, 0xfe, 0x13, 0x37}}
+			err := frame.Write(b, protocol.VersionWhatever)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(b.Bytes()).To(Equal([]byte{0x0e, 0xde, 0xad, 0xbe, 0xef, 0xca, 0xfe, 0x13, 0x37}))
+		})
+
+		It("has the correct min length", func() {
+			frame := PathChallengeFrame{}
+			Expect(frame.Length(protocol.VersionWhatever)).To(Equal(protocol.ByteCount(9)))
+		})
+	})
+})